• Journal of the Korean Magnetics Society
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• v.5 no.5
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• pp.552-555
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• 1995

The magnetic properties of Mg-Mn ferrites were investigated in the composition range of $Mg_{a}Mn_{b}Fe_{c}O_{4\pm\delta}$ (a+b+c=3) with the addition of $Al_{2}O_{3}$. In $MgO-MnO-Fe_{2}O_{3}$ ternary system, the spinel single phase existed within the composition range of MgO-50 mol%, MnO-70 mol% and $Fe_{2}O_{3}-60\;mol%$. The saturation magnetic flux density increased with the increase of $Fe_{2}O_{3}$ content and showed the maximum at the stoichiometric composition of $(Mg,Mn)Fe_{2}O_{4}$. In $Mg_{x}Mn_{1-x}Fe_{2}O_{4}(x=0.2~0.8)$ system, the saturation magnetic flux density showed the maximum at $Mg_{0.2}Mn_{0.8}Fe_{2}O_{4}$. The addition of $Al_{2}O_{3}$ resulted in the decrease of saturation magnetic flux density but increased the electrical resistivity.

• Journal of Welding and Joining
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• v.1 no.2
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• pp.76-82
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• 1983

The chemical composition of deposit metal by flux cored arc welding can be easily regulated though addition of deoxidizers and alloying elements in cored flux and fluxes of flux coored wire arc analogous to those of coated electrode. It is necessary to investigate the transfer and yield efficiency due to addition of necessary alloy elements in deposit metal. This report is made to intorduce an experimental equation from the relation between welding condition and extent of penetration, deposit metal and weld melt slag and to estimate transfer and yield efficiency of alloy components in fluxes through chemical analysis of deposit metal.

• Journal of Power Electronics
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• v.14 no.1
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• pp.194-201
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• 2014

To increase the capacity of secondary cells, an appropriate serial composition of the battery modules is essential. The unbalance that may occur due to the series connection in such a serial composition is the main cause for declines in the efficiency and performance of batteries. Various studies have been conducted on the use of a passive or active topology to eliminate the unbalance from the series circuit of battery modules. Most topologies consist of a complex structure in which the Battery Management System (BMS) detects the voltage of each module and establishes the voltage balancing in the independent electrical power converters installed on each module by comparing the module voltage. This study proposes a new magnetic flux sharing type DC/DC converter topology in order to remove voltage unbalances from batteries. The proposed topology is characterized by a design in which all of the DC/DC convertor outputs connected to the modules converge into a single transformer. In this structure, by taking a form in which all of the battery balancing type converters share magnetic flux through a single harmonic wave transformer, all of the converter voltages automatically converge to the same voltage. This paper attempts to analyze the dynamic properties of the proposed circuit by using a Programmable Synthesizer Interface Module (PSIM), which is useful for power electronics analysis, while also attempting to demonstrate the validity of the proposed circuit through experimental results.

• Journal of the Korean Ceramic Society
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• v.26 no.1
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• pp.59-66
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• 1989

Single crystals of the superconducting Y-Ba-Cu oxide were grown by a flux technique. Stoichiometric mixture with excess BaO and CuOcontent was melted at 130$0^{\circ}C$, followed by fast cooling to 108$0^{\circ}C$ to prevent crystallizing of CuO. It was then reheated to 110$0^{\circ}C$ followed by being held at this temperature to control the number of nuclei, and cooled by 5$^{\circ}C$/hr to 80$0^{\circ}C$. This procedure was repeated with various compositions and crystals were obtained in cavity. Molten solution was seperated to two parts : the upper part of almost CuO and the rest of different composition. Appropriate composition of flux was 30mol% BaO and 70mol% CuO due to the seperation of molten solution. Single crystals have the habit of thin plate with good developed (001) crystal face, XRD, EDAX and single crystal X-ray investigations were carried out. The grown crystals have tetragonal structure with the lattice parameters a=b=3.84$\AA$, c=11.7$\AA$, and the space group P4/mmm. The crystal surface were observed by SEM.

• Proceedings of the KWS Conference
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• 2009.11a
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• pp.202-204
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• 2009

Erosion is a common failure mode of materials frequently encountered in plant and power industry. Although the erosion resistance of Fe-base alloy has been inferior to the other expensive materials, it is expected that the strain-induced martensitic transformation can impart high erosion resistance to Fe-base alloy. The key technology to develop Fe-base metal cored welding wire for erosion resistant overlay welding may include the strain-induced metallurgy for hardening rate control and the welding flux metallurgy for dilution control. Sophisticated studies showed that the strain-induced martensitic transformation behavior was related to the critical strain energy which was dependent on the alloy composition. Dilution and bead shape of overlay weld were proved to be affected by metal transfer mode during gas tungsten arc welding and elements in welding fluxes. It was considered that the highly erosion resistant Fe-base overlay weld could be achieved by precise control of alloy composition to have proper level of critical strain energy for energy absorption and welding flux formulation to have small amount of deoxidizing metallic elements for dilution.

• Applied Chemistry for Engineering
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• v.10 no.6
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• pp.954-959
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• 1999

Radiation-induced grafting of 2-hydroxyethyl methacrylate(HEMA), acrylic acid(AAc) and methacrylic acid(MAAc) onto polypropylene microfiltration membrane has been studied. The effect of grafting conditions such as solvent composition(MeOH and $H_2O$) and monomer concentration on the grafting yield in investigated. The highest degree of grafting is obtained at a solvent composition of 25% $H_2O$:75% MeOH for HEMA, pure water for AAc and 50% $H_2O$:50% MeOH for MAAc. Modification of the PP membranes with hydrophilic monomers is shown to cause an increase in the water permeation flux of the membranes. It is found that HEMA is the best monomer to increase the water permeation flux and the highest water permeation flux is obtained at 99% degree of grafting. The water permeation flux of AAc-grafted PP membrane and MAAc-grafted PP membrane is very sensitive to environmental pH and $Cu^{2+}$ ion, but the water permeation flux of HEMA-grafted PP membrane scarcely depends on pH and $Cu^{2+}$ ion.

• Fire Science and Engineering
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• v.14 no.2
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• pp.33-38
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• 2000

Flux, essentially used in soldering process of PCB (Printed Circuit Board) in electronics industry, contains IPA (Isopropyl alcohol) and methanol, which are highly inflammable and explosive. Hazard Chemical Controlling Law classified methanol as toxic material and Environmental Law classified methanol as VOC (Volatile Organic Compound). So there have been pressing needs of developing substitutes for the existing Flux. New solvent which is non-flammable and main component is DCP having same specific character of the existing Flux. It's been combirated with proper composition ratio adding stabilizer. As a result, it relieved working Environment Allowance thickness 200 ppm to 470 ppm, chance of not been soldered 0.083% to 0%, spread 85% to 87%, power saving resistance 1.0$\times$$10^{12}$$\Omega$ to 6.9$\times$$10^{12}$$\Omega$, which means a lot better than the existing Flux. Therefore, Flux confirmed the chance of improving productivity, safety, environment safety and quality. Also, Flux got a satisfied result after product quality test and product reliability test.

• Journal of the Microelectronics and Packaging Society
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• v.28 no.2
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• pp.45-50
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• 2021

As the difficulty of flip chip products increases, there is a growing interest in the material of flux, which is safe from the solder wetting and reliability. In the case of no clean flux, there is merit in terms of process efficiency because there is no cleaning process. But Cu migration and delamination can be occurred if the residue remains after the reflow process. In this study, major element materials, solvent and activator, are changed and confirmed effect of non-wet and reliability in the package environment. Stability of materials were secured through storage stability evaluation, and we found out non-wet zero materials through the application of two types of solvent and activator with different boiling point and the increase of activator content. After reliability test, no delamination was found in the plane analysis, which secured the final composition of low residue flux.

• 한국연소학회:학술대회논문집
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• 2003.05a
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• pp.261-266
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• 2003

An experimental study has been conducted to evaluate the effects of $CO_{2}$ on heat transfer from hydrogen oxygen-enriched flame. Experiments were performed on flames stabilized by a co-flow swirl burner, which mounted on top of the furnace. Five composition conditions of oxidizer were chosen with replacing $N_{2}$ with $CO_{2}$. In a steady state, total and radiative heat flux rates from the flame to the wall of furnace has been measured using heat flux meters. Temperature distribution in furnace also has been checked. Increasing $CO_{2}$ ratio in the oxidizer, the dominant heat transfer mode was changed into convection from radiation. Temperature in the furnace decreased but total heat flux increased.

• Journal of The Korean Society of Agricultural Engineers
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• v.47 no.1
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• pp.51-59
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• 2005

The settling rate of the dredged soil may vary with mineral composition, grain size distribution, initial con contration and salt concentration of suspension of the site. A series of settling column test was performed to investigate the settling rate characteristics of solid suspension material from dredging and reclamation. The settling rate of soil mixed with various size of particles depended on clay fraction which showed a inherent flux. A model was developed to predict the particle flux of mixed soil from the clay flux and its applicability was verified.